docs: def set_constants(self, *constants, verbose=True):
          """Set the constants associated with the data.
  
          Parameters
          ----------
          constants : str
              Expressions for the new set of constants.
          verbose : boolean (optional)
              Toggle talkback. Default is True
  
          See Also
          --------
          transform
              Similar method except for axes.
          create_constant
              Add an individual constant.
          remove_constant
              Remove an individual constant.
          """
          # create
          new = []
          current = {c.expression: c for c in self._constants}
          for expression in constants:
              constant = current.get(expression, Constant(self, expression))
              new.append(constant)
          self._constants = new
          # units
          for c in self._constants:
              if c.units is None:
                  c.convert(c.variables[0].units)
          # finish
          self.flush()
          self._on_constants_updated()